Integration of high performance wireless radios (e.g., millimeter wave radios) on low loss package substrates raises a variety of challenges. For example, a thick dielectric layer may be used between a radiating element such as an antenna and an underlying ground plane in order for the integrated antenna to cover a broad frequency band (e.g., 7 GHz around 60 GHz), which may result in ultra-thick package substrates. A variety of low loss substrate materials may provide better electrical performance at frequencies of integrated wireless radios, however such low loss substrate materials may be more flexible and may not have sufficient mechanical stability to be processed as ultra-thick layers for antenna integration. For example, flexible materials may be more susceptible to package warpage. Accordingly, current solutions may utilize more rigid materials such as, for example, low temperature co-fired ceramic (LTCC), which may also be a more costly material. In some cases, materials that increase mechanical rigidity of a substrate material may increase surface roughness, which may lead to increased conductor losses at higher frequencies. Structurally rigid configurations that are thinner and/or cheaper with lower loss and surface roughness may be desirable.